multi-architecture docker pipeline in Drone CI

.drone.yml

---

kind: pipeline
type: docker
name: linux-amd64

trigger:
  branch:
    - myapp
  event:
    - push
    - custom

platform:
  arch: amd64
  os: linux

clone:
  skip_verify: yes

steps:
  - name: build
    image: docker:20-dind
    volumes:
      - name: dockersock
        path: /var/run
    commands:
      - sleep 5 # give docker enough time to start
      - docker build --network host -t registry.local:5000/myapp:${DRONE_COMMIT_SHA:0:8}-linux-amd64 .

  - name: push
    image: docker:20-dind
    volumes:
      - name: dockersock
        path: /var/run
    commands:
      - docker push registry.local:5000/myapp:${DRONE_COMMIT_SHA:0:8}-linux-amd64

services:
  - name: docker
    image: docker:20-dind
    privileged: true
    entrypoint: 
      - "dockerd"
    volumes:
      - name: dockersock
        path: /var/run
    command: 
      - "--host=unix:///var/run/docker.sock"
      - "--insecure-registry=registry.local:5000"

volumes:
  - name: dockersock
    temp: {}

---

kind: pipeline
type: docker
name: linux-arm64

trigger:
  branch:
    - myapp
  event:
    - push
    - custom

platform:
  arch: arm64
  os: linux

clone:
  skip_verify: yes

steps:
  - name: build
    image: docker:20-dind
    volumes:
      - name: dockersock
        path: /var/run
    commands:
      - sleep 5 # give docker enough time to start
      - docker build --network host -t registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8}-linux-arm64 .

  - name: push
    image: docker:20-dind
    volumes:
      - name: dockersock
        path: /var/run
    commands:
      - docker push registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8}-linux-arm64

services:
  - name: docker
    image: docker:20-dind
    privileged: true
    entrypoint: 
      - "dockerd"
    volumes:
      - name: dockersock
        path: /var/run
    command: 
      - "--host=unix:///var/run/docker.sock"
      - "--insecure-registry=registry.local:5000"

volumes:
  - name: dockersock
    temp: {}

---

kind: pipeline
type: docker
name: manifest

trigger:
  branch:
    - myapp
  event:
    - push
    - custom

clone:
  skip_verify: yes

steps:
  - name: create && push
    image: docker:20-dind
    volumes:
      - name: dockersock
        path: /var/run
    commands:
      - sleep 5 # give docker enough time to start
      - docker manifest create --insecure registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8} --amend registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8}-linux-amd64 --amend registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8}-linux-arm64
      - docker manifest push --insecure registry.local:5000/${DRONE_COMMIT_BRANCH}:${DRONE_COMMIT_SHA:0:8}

services:
  - name: docker
    image: docker:20-dind
    privileged: true
    entrypoint: 
      - "dockerd"
    volumes:
      - name: dockersock
        path: /var/run
    command: 
      - "--experimental"
      - "--host=unix:///var/run/docker.sock"
      - "--insecure-registry=registry.local:5000"

volumes:
  - name: dockersock
    temp: {}

depends_on:
  - linux-amd64
  - linux-arm64

This pipeline is based on examples in Drone and Docker documentation. Although it doesn't use any of the official drone plugins since they're mostly outdated and sometimes even broken, also the same result can be easily achieved only with the official docker:dind image
(it took me several hours to make this work, just putting it here in case someone else has use for it).