tricky

• configure files

  • docker desktop

• check docker layer

  • install

• docker with proxy

  • docker pull

  • docker build

  • via daemon.json

  • docker build with GPG key proxy

• docker for osx

  • docker: command cannot be found

• command-line auto completion

  • Linux

  • osx

• others

• complete alias

• get tags

  • from artifactory

  • from docker hub

• run inside windows docker image

  • add contents

  • get contents

  • list item

  • execute

configure files

docker desktop

[!TIP|label:references:]

• Change your Docker Desktop settings

FILE	MACOS	WINDOWS	LINUX
settings-store.json settings.json(<=v4.34)	~/Library/Group Containers/group.com.docker/settings-store.json	%APPDATA%\Docker\settings-store.json	~/.docker/settings-store.json
.com.apple.containermanagerd.metadata.plist	~/Library/Containers/com.docker.docker/.com.apple.containermanagerd.metadata.plist	-	-

{
  "AcceptCanaryUpdates": false,
  "ActiveOrganizationName": "",
  "AllowBetaFeatures": true,
  "AllowExperimentalFeatures": true,
  "AnalyticsEnabled": true,
  "AutoDownloadUpdates": false,
  "AutoPauseTimedActivitySeconds": 30,
  "AutoPauseTimeoutSeconds": 300,
  "AutoStart": false,
  "BackupData": false,
  "BlockDockerLoad": false,
  "ContainerTerminal": "integrated",
  "ContainersOverrideProxyExclude": "",
  "ContainersOverrideProxyHTTP": "",
  "ContainersOverrideProxyHTTPS": "",
  "ContainersOverrideProxyPAC": "",
  "ContainersOverrideProxyTCP": "",
  "ContainersOverrideProxyTransparentPorts": "80,443",
  "ContainersProxyHTTPMode": "",
  "Cpus": 12,
  "CredentialHelper": "docker-credential-osxkeychain",
  "CustomWslDistroDir": "",
  "DataFolder": "/Users/marslo/Library/Containers/com.docker.docker/Data/vms/0/data",
  "DefaultSnapshotter": "overlayfs",
  "DeprecatedCgroupv1": false,
  "DesktopTerminalEnabled": false,
  "DevEnvironmentsEnabled": false,
  "DisableHardwareAcceleration": false,
  "DisableUpdate": false,
  "DiskFlush": "os",
  "DiskSizeMiB": 61035,
  "DiskStats": "",
  "DiskTRIM": true,
  "DisplayRestartDialog": true,
  "DisplaySwitchWinLinContainers": false,
  "Displayed18362Deprecation": false,
  "DisplayedElectronPopup": [],
  "DisplayedOnboarding": true,
  "DockerAppLaunchPath": "/Applications/Docker.app",
  "DockerBinInstallPath": "system",
  "DockerDebugDefaultEnabled": false,
  "DogfoodFeatureFlagsEnabled": false,
  "ECIDockerSocketAllowDerivedImages": true,
  "ECIDockerSocketCmdList": [],
  "ECIDockerSocketCmdListType": "deny",
  "ECIDockerSocketImgList": [],
  "EnableDefaultDockerSocket": true,
  "EnableIntegrationWithDefaultWslDistro": false,
  "EnableIntegrityCheck": true,
  "EnableSegmentDebug": false,
  "EnableWasmShims": false,
  "EnhancedContainerIsolation": false,
  "ExposeDockerAPIOnTCP2375": false,
  "ExtensionsEnabled": true,
  "ExtensionsPrivateMarketplace": false,
  "ExtensionsPrivateMarketplaceAdminContactURL": "",
  "FilesharingDirectories": [
    "/Users",
    "/Volumes",
    "/private",
    "/tmp",
    "/var/folders"
  ],
  "HostNetworkingEnabled": false,
  "IPv4Only": false,
  "IPv6Only": false,
  "KernelForUDP": false,
  "KubernetesEnabled": false,
  "KubernetesImagesRepository": "",
  "KubernetesMode": "",
  "KubernetesNodesCount": 0,
  "LastContainerdSnapshotterEnable": 1730830362,
  "LastLoginDate": 0,
  "LatestBannerKey": "",
  "LicenseTermsVersion": 2,
  "LifecycleTimeoutSeconds": 600,
  "MemoryMiB": 8092,
  "NetworkType": "gvisor",
  "OnlyMarketplaceExtensions": true,
  "OpenUIOnStartupDisabled": false,
  "OverrideProxyExclude": "",
  "OverrideProxyHTTP": "",
  "OverrideProxyHTTPS": "",
  "OverrideProxyPAC": "",
  "OverrideProxyTCP": "",
  "OverrideWindowsDockerdPort": -1,
  "ProxyEnableKerberosNTLM": false,
  "ProxyHTTPMode": "system",
  "ProxyLocalhostPort": 0,
  "RequireVmnetd": true,
  "RunWinServiceInWslMode": false,
  "SbomIndexing": true,
  "ScoutNotificationPopupsEnabled": true,
  "ScoutOsNotificationsEnabled": false,
  "SettingsVersion": 40,
  "ShowAnnouncementNotifications": true,
  "ShowExtensionsSystemContainers": false,
  "ShowGeneralNotifications": true,
  "ShowInstallScreen": false,
  "ShowKubernetesSystemContainers": false,
  "ShowPromotionalNotifications": true,
  "ShowSurveyNotifications": true,
  "SkipUpdateToWSLPrompt": false,
  "SkipWSLMountPerfWarning": false,
  "SocksProxyPort": 0,
  "SwapMiB": 1024,
  "SynchronizedDirectories": [],
  "ThemeSource": "system",
  "UpdateAvailableTime": 0,
  "UpdateHostsFile": false,
  "UpdateInstallTime": 0,
  "UseBackgroundIndexing": false,
  "UseContainerdSnapshotter": true,
  "UseCredentialHelper": true,
  "UseGrpcfuse": true,
  "UseLibkrun": false,
  "UseNightlyBuildUpdates": false,
  "UseResourceSaver": true,
  "UseVirtualizationFramework": true,
  "UseVirtualizationFrameworkRosetta": true,
  "UseVirtualizationFrameworkVirtioFS": true,
  "UseVpnkit": true,
  "UseWindowsContainers": false,
  "VpnKitAllowedBindAddresses": "0.0.0.0",
  "VpnKitMTU": 1500,
  "VpnKitMaxConnections": 2000,
  "VpnKitMaxPortIdleTime": 300,
  "VpnKitTransparentProxy": true,
  "VpnkitCIDR": "192.168.65.0/24",
  "WslDiskCompactionThresholdGb": 0,
  "WslEnableGrpcfuse": false,
  "WslEngineEnabled": false,
  "WslInstallMode": "installLatestWsl",
  "WslUpdateRequired": false
}

$ defaults read ~/Library/Containers/com.docker.docker/.com.apple.containermanagerd.metadata.plist
{
    MCMMetadataActiveDPClass = "-1";
    MCMMetadataContentClass = 2;
    MCMMetadataIdentifier = "com.docker.docker";
    MCMMetadataSchemaVersion = 0;
    MCMMetadataUUID = "386F734E-BD40-4755-87A2-DDF4ABD17A64";
    MCMMetadataUserIdentity =     {
        personaUniqueString = "2EDCF936-1321-4383-A54D-3784F660E452";
        posixGID = 20;
        posixUID = 503;
        type = 0;
        version = 2;
    };
    MCMMetadataVersion = 7;
}

check docker layer

[!NOTE|label:references:]

• wagoodman/dive

install

$ DOWNLOAD_URL="$(curl -fsSL https://api.github.com/repos/wagoodman/dive/releases/latest |
   jq -r '.assets[] | select(.name | endswith("_linux_amd64.deb")) | .browser_download_url')"
$ curl -OL "${DOWNLOAD_URL}"

$ DIVE_VERSION="$(curl -fsSL https://api.github.com/repos/wagoodman/dive/releases/latest | jq -r .tag_name)"
# or
$ DIVE_VERSION=$(curl -sL "https://api.github.com/repos/wagoodman/dive/releases/latest" | grep '"tag_name":' | sed -E 's/.*"v([^"]+)".*/\1/')
$ curl -OL https://github.com/wagoodman/dive/releases/download/v${DIVE_VERSION}/dive_${DIVE_VERSION}_linux_amd64.deb

$ sudo apt install ./dive_${DIVE_VERSION}_linux_amd64.deb

docker with proxy

[!NOTE|label:references:]

• Custom Docker daemon options

  • control and configure Docker with systemd

• Configure the Docker daemon to use a proxy server

• Running a Docker daemon behind an HTTPS_PROXY

docker pull

$ sudo mkdir -p /etc/systemd/system/docker.service.d
$ cat /etc/systemd/system/docker.service.d/http-proxy.conf
[Service]
Environment="HTTPS_PROXY=http://sample.proxy.com:80"
Environment="HTTP_PROXY=http://sample.proxy.com:80"
Environment="ALL_PROXY=http://sample.proxy.com:80"
systemctl daemon-reload;systemctl start docker

$ sudo systemctl daemon-reload
$ sudo systemctl restart docker

# verify
$ systemctl show docker --property Environment
Environment=HTTPS_PROXY=http://sample.proxy.com:80 HTTP_PROXY=http://sample.proxy.com:80 ALL_PROXY=http://sample.proxy.com:80

• for socks5

  $ [ ! -d /etc/systemd/system/docker.service.d ] && sudo mkdir -p /etc/systemd/system/docker.service.d
  $ sudo bash -c "cat > /etc/systemd/system/docker.service.d/socks5-proxy.conf" << EOF
  [Service]
  Environment="ALL_PROXY=socks5://sample.proxy.com:80"
  Environment="NO_PROXY=localhost,127.0.0.1,130.147.0.0/16,130.145.0.0/16"
  EOF
  
  $ sudo systemctl daemon-reload
  $ sudo systemctl enable docker.service
  $ sudo systemctl restart docker.service

• or

  # for rootless mode
  $ mkdir -p ~/.config/systemd/user/docker.service.d/
  # or regular mode
  $ sudo mkdir -p /etc/systemd/system/docker.service.d
  
  $ sudo bash -c "cat > /etc/systemd/system/docker.service.d" << EOF
  [Service]
  Environment="HTTP_PROXY=http://sample.proxy.com:80"
  Environment="HTTPS_PROXY=https://sample.proxy.com:443"
  Environment="NO_PROXY=localhost,127.0.0.1,sample.docker-registry.com,.corp"
  EOF
  
  $ sudo systemctl daemon-reload
  $ sudo systemctl restart docker
  
  # verify
  $ systemctl show docker --property Environment
  Environment=HTTP_PROXY=http://sample.proxy.com:80 HTTPS_PROXY=http://sample.proxy.com:443 NO_PROXY=localhost,127.0.0.1,sample.docker-registry.com,.corp

docker build

$ mkdir -p ~/.docker
$ cat > ~/.docker/config.json << EFO
{
 "proxies":
 {
   "default":
   {
     "httpProxy": "http://sample.proxy.com:80",
     "httpsProxy": "http://sample.proxy.com:80",
     "allProxy": "http://sample.proxy.com:80",
     "noProxy": "*.sample.domain1.com,.domain2.com,127.0.0.0/8"
   }
 }
}
EOF

• or via --build-arg:

  $ docker build \
           --build-arg http_proxy=http://sample.proxy.com:80 \
           --build-arg https_proxy=http://sample.proxy.com:443 \
          .

• details

  VARIABLE	DOCKERFILE EXAMPLE	DOCKER RUN EXAMPLE
  HTTP_PROXY	ENV HTTP_PROXY="http://sample.proxy.com:80"	--env HTTP_PROXY="http://sample.proxy.com:80"
  HTTPS_PROXY	ENV HTTPS_PROXY="https://sample.proxy.com:80"	--env HTTPS_PROXY="https://sample.proxy.com:80"
  FTP_PROXY	ENV FTP_PROXY="ftp://sample.proxy.com:80"	--env FTP_PROXY="ftp://sample.proxy.com:80"
  NO_PROXY	ENV NO_PROXY="*.sample.domain1.com,.domain2.com"	--env NO_PROXY="*.sample.domain1.com,.domain2.com,127.0.0.0/8"

via daemon.json

[!TIP]

• * iMarslo: dockerd

• daemon.json

• Proxy configuration

$ cat /etc/docker/daemon.json
{
  "proxies": {
    "http-proxy": "http://proxy.example.com:80",
    "https-proxy": "https://proxy.example.com:443",
    "no-proxy": "*.test.example.com,.example.org"
  }
}

docker build with GPG key proxy

• without proxy

  ...
  gpg --batch \
      --keyserver https://keyserver.ubuntu.com:80 \
      --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831E
  ...
  
  # result
  gpg: keyserver receive failed: Connection timed out

• GPG with proxy

  ...
  apt-key adv --keyserver-options http-proxy=http://sample.proxy.com:80 \
              --keyserver hkp://keyserver.ubuntu.com:80 \
              --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF \
  ...
  
  # result
  Executing: /tmp/apt-key-gpghome.uegAG54mKu/gpg.1.sh --keyserver-options http-proxy=http://sample.proxy.com:80 --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
  gpg: key A6A19B38D3D831EF: 2 signatures not checked due to missing keys
  gpg: key A6A19B38D3D831EF: public key "Xamarin Public Jenkins (auto-signing) <[e-mail]>" imported
  gpg: Total number processed: 1
  gpg:               imported: 1
  gpg: keybox '/tmp/tmp.jad0qVCQ6v/pubring.kbx' created
  gpg: WARNING: nothing exported
  Warning: apt-key output should not be parsed (stdout is not a terminal)

docker for osx

[!TIP|label:references:]

• #6793: Docker not found when freshly installed on Mac

• Installing symlinks

docker: command cannot be found

docker desktop advanced Settings

• using user

  $ export $HOME/.docker/bin:$PATH

• using system

  $ ln -sf $HOME/.docker/bin/docker /usr/local/bin/docker
  # or
  $ ln -s /Applications/Docker.app/Contents/Resources/bin/docker /usr/local/bin/docker
  
  $ sudo ln -s -f $HOME/.docker/run/docker.sock /var/run/docker.sock

  • modify ~/.docker/config.json if necessary

    {
            "auths": {},
    -        "credsStore": "desktop",
    +        "credStore": "desktop",
            "currentContext": "desktop-linux"
    }

command-line auto completion

[!TIP] reference:

• Enable Docker command-line auto completion in bash on Centos/Ubuntu

• completion/bash/docker

• Perform tab-completion for aliases in Bash

Linux

$ dpkg -L docker-ce-cli | grep completion
/usr/share/bash-completion
/usr/share/bash-completion/completions
/usr/share/bash-completion/completions/docker
/usr/share/fish/vendor_completions.d
/usr/share/fish/vendor_completions.d/docker.fish
/usr/share/zsh/vendor-completions
/usr/share/zsh/vendor-completions/_docker

• rpm

  $ rpm -ql docker-ce | grep completion
  /usr/share/bash-completion/completions/docker
  /usr/share/fish/vendor_completions.d/docker.fish
  /usr/share/zsh/vendor-completions/_docker

setup in bashrc

source /usr/share/bash-completion/completions/docker
alias d='docker'
alias dp='docker ps'

while read -r _i; do
  complete -F _docker "${_i}"
done < <(alias | grep docker | sed '/^alias /!d;s/^alias //;s/=.*$//')

• more info

  $ source /usr/share/bash-completion/completions/docker
  $ type _docker | head
  _docker is a function
  _docker ()
  {
    local previous_extglob_setting=$(shopt -p extglob);
    shopt -s extglob;
  }

osx

$ la '/Applications/Docker.app/Contents/Resources/etc'
total 332K
-rwxr-xr-x 1 marslo admin 124K Nov  9 21:50 docker.zsh-completion
-rwxr-xr-x 1 marslo admin  51K Nov  9 21:50 docker.fish-completion
-rwxr-xr-x 1 marslo admin 114K Nov  9 21:50 docker.bash-completion
-rw-r--r-- 1 marslo admin  18K Nov  9 21:50 docker-compose.zsh-completion
-rw-r--r-- 1 marslo admin 1.7K Nov  9 21:50 docker-compose.fish-completion
-rwxr-xr-x 1 marslo admin  13K Nov  9 21:50 docker-compose.bash-completion

$ ln -sf '/Applications/Docker.app/Contents/Resources/etc/docker.bash-completion' $(brew --prefix)/etc/bash_completion.d/docker
$ ln -sf '/Applications/Docker.app/Contents/Resources/etc/docker-compose.bash-completion' $(brew --prefix)/etc/bash_completion.d/docker-compose

• setup in bashrc

  dockerComp="$(brew --prefix)/etc/bash_completion.d/docker"
  dockerComposeComp="$(brew --prefix)/etc/bash_completion.d/docker-compose"
  [ -f "${dockerComp}" ] && source "${dockerComp}"
  [ -f "${dockerComposeComp}" ] && source "${dockerComposeComp}"
  
  alias d='docker'
  alias dp='docker ps'
  alias dls='docker ps -l -q'
  alias dps='docker ps -l -a'
  alias di='docker images'
  alias dip="docker inspect --format '{{ .NetworkSettings.IPAddress }}'"
  
  while read -r _i; do
    complete -F _docker "${_i}"
  done < <(alias | grep docker | sed '/^alias /!d;s/^alias //;s/=.*$//')

others

• _completion_loader

  _completion_loader()
  {
    . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124
  }
  complete -D -F _completion_loader

complete alias

# for Linux
$ sudo curl -sSLg https://raw.githubusercontent.com/cykerway/complete-alias/master/complete_alias \
            -o /etc/bash_completion.d/complete_alias

# for osx
$ sudo curl -sSLg https://raw.githubusercontent.com/cykerway/complete-alias/master/complete_alias \
            -o $(brew --prefix)/etc/bash_completion.d/complete_alias

• setup in bash

  source /etc/bash_completion.d/complete_alias
  #
  source $(brew --prefix)/etc/bash_completion.d/complete_alias
  
  while read -r _i; do
    complete -F _complete_alias "${_i}"
  done < <(alias | grep -E 'docker|kubectl' | sed '/^alias /!d;s/^alias //;s/=.*$//')

get tags

from artifactory

• list repos

  example: the docker registry in artifactory named docker

$ curl -sS https://artifactory.sample.com/v2/docker/_catalog |
       jq -r .repositories[]

• or

  $ curl -sS -X GET https://artifactory.sample.com/artifactory/api/docker/docker/v2/_catalog |
         jq -r .repositories[]

• list tags

  example: get tags from repo devops/ubuntu

  $ curl -sS https://artifactory.sample.com/artifactory/v2/docker/devops/ubuntu/tags/list [ | jq -r .tags[] ]

  • or

    $ curl -sS -X GET https://artifactory.sample.com/artifactory/api/docker/docker/v2/devops/ubuntu/tags/list

get image:tag via jf cli

$ jf rt search docker/devops/kwciagent/kw23.4-4.0.1** |
  jq -r '.[].props | select(."docker.manifest" != null) | [ ."docker.manifest"[0], ."docker.repoName"[0] ] | "\(.[1]):\(.[0])"'
devops/kwciagent:kw23.4-4.0.1-py310-jammy-dind
devops/kwciagent:kw23.4-4.0.1-py310-jammy-dind-v96-906236c7d

from docker hub

$ curl -sS 'https://hub.docker.com/v2/repositories/jenkins/jenkins/tags' |
       jq --raw-output .results[].name

jdk8-openj9-windowsservercore-1809
jdk11-hotspot-windowsservercore-1809
jdk11-openj9-windowsservercore-1809
windowsservercore-1809
jdk8-hotspot-windowsservercore-1809
2.249.3-lts-centos7
lts-centos7
centos7
2.249.3-lts-centos
lts-centos

• get more

  $ curl -sS 'https://hub.docker.com/v2/repositories/jenkins/jenkins/tags?page_size=100&ordering=last_updated' |
         jq --raw-output .results[].name |
         sort

  • or

    $ curl -sS https://hub.docker.com/v2/repositories/jenkins/jenkins/tags?page=2 |
           jq '."results"[]["name"]' |
           sort

• get multiple pages

  $ while read -r _i; do
      curl -sSgk "https://registry.hub.docker.com/v2/repositories/jenkins/jenkins/tags?&page=${_i}&page_size=100" |
           jq -r '.results[] | select( .name | contains("-lts-") ) | .name';
    done < <(echo {1..10} | fmt -1)

• via docker registry tags/list API v2

  [!NOTE|label:references:]

  • an OAuth bearer token

  • Docker Registry API V2

  • samples:

    • How can I list all tags for a Docker image on a remote registry?

    • Get list of docker tags available to pull from command line?

    • robv8r/docker_tags.sh

  $ cat > docker-tags.sh << EOF
  #!/usr/bin/env bash
  set -eu -o pipefail
  docker_tags() {
    item="$1"
    case "$item" in
        */*) :                    ;; # namespace/repository syntax, leave as is
          *) item="library/$item" ;; # bare repository name (docker official image); must convert to namespace/repository syntax
    esac
    authUrl="https://auth.docker.io/token?service=registry.docker.io&scope=repository:$item:pull"
    token="$(curl -fsSL "$authUrl" | jq --raw-output '.token')"
    tagsUrl="https://registry-1.docker.io/v2/$item/tags/list"
    curl -fsSL -H "Accept: application/json" -H "Authorization: Bearer $token" "$tagsUrl" | jq --raw-output '.tags[]'
  }
  docker_tags "$@"
  EOF
  
  $ bash docker-tags.sh jenkins/jenkins | sort -r | grep --color=never -- '-lts-jdk11' | head -3
  2.440.2-lts-jdk11
  2.440.1-lts-jdk11
  2.426.3-lts-jdk11

simple script for get tags

#!/bin/sh
#
# Simple script that will display docker repository tags.
#
# Usage:
#   $ docker-show-repo-tags.sh ubuntu centos

for _r in $* ; do
  curl -sS "https://registry.hub.docker.com/v2/repositories/library/$_r/tags/" |
       sed -e 's/,/,\n/g' -e 's/\[/\[\n/g' |
       grep '"name"' |
       awk -F\" '{print $4;}' |
       sort -fu |
       sed -e "s/^/${_r}:/"
done

get current container ID

$ basename $(cat /proc/self/cpuset)
ab8c1732f1a3fdb46b9f9a477f0fbcc1d23c6787d7532648242a76d6eb1e8b84

• or

  $ hostname
  ab8c1732f1a3

get volume from container ID

$ docker inspect -f '{{ .Mounts }}' <container ID>

• or

  $ docker inspect <container ID> |
           grep volume

• or get all

  $ docker ps -a --no-trunc --format "{{.ID}}\t{{.Names}}\t{{.Mounts}}"

• or

  $ docker inspect <container ID> |
           jq --raw-output .[].Mounts

• or

  $ docker ps -q |
           xargs docker container inspect -f '{{ .Name }} {{ .HostConfig.Binds }}'

mount volume in DinD

reference:

• Mounting Volumes in Sibling Containers with Gitlab CI

• Mount volumes from container (--volumes-from)

• Kubernetes emptyDir is not the same as Docker's volumes-from

$ cid=$(basename $(cat /proc/self/cpuset))
$ VOLUME_OPTION="--volumes-from ${cid}:rw"
$ docker run <...> ${VOLUME_OPTION}

run inside windows docker image

add contents

> docker exec [-w 'C:\workspace'] <docker-id> powershell "Set-Content -Path '_cmd.ps1' -Value 'python --version'"

• for multiple line contents

  > docker exec [-w 'C:\workspace'] <docker-id>' powershell "Set-Content -Path .\test.py -Value '# content of test_sample.py
  >> def func(x):
  >>     return x + 1
  >>
  >>
  >> def test_answer():
  >>     assert func(4) == 5'"

get contents

> docker exec [-w 'C:\workspace'] <docker-id> powershell "Get-Content '_cmd.ps1'"

• equivalent tail -f

  > docker exec [-w 'C:\workspace'] <docker-id> powershell "Get-Content '_cmd.ps1' -Wait"

• equivalent tail -10

  > docker exec [-w 'C:\workspace'] <docker-id> powershell "Get-Content '_cmd.ps1' -Tail 10"

list item

> docker exec [-w 'C:\workspace'] <docker-id> powershell Get-ChildItem .
> docker exec [-w 'C:\workspace'] <docker-id> powershell Get-ChildItem ..\

execute

> docker exec [-w 'C:\workspace'] <docker-id> powershell .\_cmd.ps1

# or
> docker exec [-w 'C:\workspace'] <docker-id> powershell "Invoke-Expression '.\_cmd.ps1' > log.txt"

# or redirect via `Out-File`
> docker exec [-w 'C:\workspace'] <docker-id> powershell "Invoke-Expression '.\_cmd.ps1' | Out-File -FilePath log.txt"