Export swarm stack as Docker Compose

compost.sh

#!/bin/bash

list_stacks() {
    echo $(docker stack ls --format '{{ .Name }}')
}

# returns a list of identifiers for all services in a stack
list_stack_service_ids () {
    echo $(docker service ls --filter label=com.docker.stack.namespace=$1 -q)
}

# Returns a list of unique identifiers for secrets used in a stack
list_stack_secret_ids () {
    local service_ids="$(list_stack_service_ids $1)"
    local secret_ids=$(docker service inspect --format '{{- range .Spec.TaskTemplate.ContainerSpec.Secrets }}
{{ .SecretID }}  
{{- end }}' $service_ids)
    # make the list unique
    echo $secret_ids | xargs -n1 | sort -u | xargs
}

# Returns a list of unique identifiers for volumes used in a stack
list_stack_volume_names () {
    local service_ids="$(list_stack_service_ids $1)"
    local config_ids=$(docker service inspect --format '{{- range .Spec.TaskTemplate.ContainerSpec.Mounts }}
{{- if eq .Type "volume" }}
{{ .Source }}
{{- end }}{{- end }}' $service_ids)
    # make the list unique
    echo $config_ids | xargs -n1 | sort -u | xargs
}

# Returns a list of unique identifiers for configs used in a stack
list_stack_config_ids () {
    local service_ids="$(list_stack_service_ids $1)"
    local config_ids=$(docker service inspect --format '{{- range .Spec.TaskTemplate.ContainerSpec.Configs }}
{{ .ConfigID }}  
{{- end}}' $service_ids)
    # make the list unique
    echo $config_ids | xargs -n1 | sort -u | xargs
}

# Outputs the Docker compose top-level services element.
export_services () {
    local service_ids="$(list_stack_service_ids $1)"
    local services="$(docker service inspect --format '  {{ .Spec.Name }}:
    image: {{ index (split .Spec.TaskTemplate.ContainerSpec.Image "@") 0 }}
    {{- if .Spec.EndpointSpec.Ports }}
    ports:
    {{- range .Spec.EndpointSpec.Ports }}
      - {{ .PublishedPort }}:{{ .TargetPort }}
    {{- end }}
    {{- end }}
    {{- if .Spec.TaskTemplate.ContainerSpec.Mounts }}
    volumes:
    {{- $stack := index .Spec.Labels "com.docker.stack.namespace" }}
    {{- range .Spec.TaskTemplate.ContainerSpec.Mounts }}
    {{- $source_without_stack := slice .Source (len (print ($stack) "_")) }}
    {{- if eq .Type "volume" }}
      - {{ $source_without_stack }}:{{ .Target }}
    {{- end }}
    {{- end }}
    {{- end }}
    deploy:
      {{- if .Spec.Mode.Replicated }}
      mode: replicated
      {{- end }}
      replicas: {{ .Spec.Mode.Replicated.Replicas }}
      {{- $first := 0 }}
      {{- range $key, $value := .Spec.Labels }}
      {{- if and (ne $key "com.docker.stack.image") (ne $key "com.docker.stack.namespace") }}
      {{- if eq $first 0 }}
      labels:
      {{- $first = 1}}
      {{- end }}
        - {{ $key }}="{{ $value }}"
      {{- end }}
      {{- end }}
    {{- if .Spec.TaskTemplate.ContainerSpec.Env }}
    environment:
    {{- range .Spec.TaskTemplate.ContainerSpec.Env }}
      - {{ index (split . "=") 0 }}="{{ index (split . "=") 1 }}"
    {{- end}}
    {{- end}}
    {{- if .Spec.TaskTemplate.ContainerSpec.Configs }}
    configs:
    {{- range .Spec.TaskTemplate.ContainerSpec.Configs }}
      - {{ .File.Name }}
    {{- end }}
    {{- end }}
    {{- if .Spec.TaskTemplate.ContainerSpec.Secrets }}
    secrets:
    {{- range .Spec.TaskTemplate.ContainerSpec.Secrets }}
      - {{ .File.Name }}
    {{- end }}
    {{- end }}
' $service_ids)"
    printf "services:\n$services"
}

# Outputs the Docker compose top-level configs element. Configs
# will be created from files in the subfolder "configs".
export_configs () {
    local config_ids="$(list_stack_config_ids $1)"
    # TODO fix the extra line break between secrets
    local configs="$(docker config inspect --format '{{ $name_without_stack := slice .Spec.Name (len (print (index .Spec.Labels "com.docker.stack.namespace") "_")) -}}
  {{ print "  " }}{{ $name_without_stack -}}:
    file: configs/{{ .Spec.Name -}}' $config_ids)"
    printf "configs:\n$configs"
}

# Outputs the Docker compose top-level secrets element. Secrets
# will be created from files in the subfolder "secrets".
export_secrets () {
    local secret_ids="$(list_stack_secret_ids $1)"
    local secrets="$(docker secret inspect --format '{{ $name_without_stack := slice .Spec.Name (len (print (index .Spec.Labels "com.docker.stack.namespace") "_")) -}}
  {{ print "  " }}{{ $name_without_stack }}:
    file: secrets/{{ .Spec.Name }}' $secret_ids)"
    printf "secrets:\n$secrets"
}

export_volumes () {
    local volume_names="$(list_stack_volume_names $1)"
    local volumes="$(docker volume inspect --format '{{ $name_without_stack := slice .Name (len (print (index .Labels "com.docker.stack.namespace") "_")) -}}
  {{ print "  " }}{{ $name_without_stack }}:
    driver_opts:
      type: "{{ .Options.type }}"
      o: "{{ .Options.o }}"
      device: "{{ .Options.device }}"' $volume_names)"
    printf "volumes:\n$volumes"
}

export_stack () {
    printf "version: \"3.9\"\n"
    printf "$(export_services $1)\n\n"
    printf "$(export_configs $1)\n\n"
    printf "$(export_secrets $1)\n\n"
    printf "$(export_volumes $1)\n\n"
}

export_stack $1
exit 0

# STACK_FOLDER=backup
# STACKS=$(list_stacks)

# mkdir -p $STACK_FOLDER
# for i in $STACKS
# do
#     file="${STACK_FOLDER}/${i}-docker-compose.yml"
#     # printf "$(list_stack_volume_names $1)"
#     printf "version: \"3.9\"\n" > $file
#     printf "$(export_services $i)\n\n" >> $file
#     printf "$(export_configs $i)\n\n" >> $file
#     printf "$(export_secrets $i)\n\n" >> $file
#     printf "$(export_volumes $i)\n\n" >> $file
# done