Добавить ssh ключ в drone

Конфига .drone.yml:

kind: pipeline
name: default
steps:
- name: test
  image: alpine:3.8
  environment:
    SSH_KEY:
      from_secret: ssh_key
  commands:
  - echo "$SSH_KEY"

В интерфейсе добавить ключ:

ssh_key="-----BEGIN RSA PRIVATE KEY-----\nMIIEpAIBAAKCAQEA04up8hoqzS1+APIB0RhjXyObwHQnOzhAk5Bd7mhkSbPkyhP1\n..."