adding item to array for multiple paths with unexpected result

[ak-at-gvl]

Bug-Desciption
My use case is to add an environment variable to all given services in a docker-compose.yml file – without knowing the service names.
Unfortunately the specific list of environment-variables of each services is not appended with the new variable, but only the very first occurrence of the array is appended correctly and then copied wrongly the whole resulting array of the first service to all other services.

Version of yq: 4.4.1 & 4.6.1
Operating system: mac & linux
Installed on linux via:

wget "https://github.com/mikefarah/yq/releases/download/v4.6.1/yq_linux_amd64" -O /usr/bin/yq && chmod +x /usr/bin/yq

on mac via homebrew

Input Yaml

sample.yaml:

version: "1.2.3"
services:
  svc1:
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
  svc2:
    environment:
      - ENV_VAR2_1
      - ENV_VAR2_2
      - ENV_VAR2_3
      - ENV_VAR2_4
  svc3:
    environment:
      - ENV_VAR3_1
      - ENV_VAR3_2
      - ENV_VAR3_3
  svc4:
    image: busybox:latest

Command
The command i ran:

yq eval '.services[].environment += ["NEW_ARRAY_ENTRY"]' sample.yaml

Actual behavior

version: "1.2.3"
services:
  svc1:
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
      - NEW_ARRAY_ENTRY
  svc2:
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
      - NEW_ARRAY_ENTRY
  svc3:
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
      - NEW_ARRAY_ENTRY
  svc4:
    image: busybox:latest
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
      - NEW_ARRAY_ENTRY

Expected behavior

version: "1.2.3"
services:
  svc1:
    environment:
      - ENV_VAR1_1
      - ENV_VAR1_2
      - NEW_ARRAY_ENTRY
  svc2:
    environment:
      - ENV_VAR2_1
      - ENV_VAR2_2
      - ENV_VAR2_3
      - ENV_VAR2_4
      - NEW_ARRAY_ENTRY
  svc3:
    environment:
      - ENV_VAR3_1
      - ENV_VAR3_2
      - ENV_VAR3_3
      - NEW_ARRAY_ENTRY
  svc4:
    image: busybox:latest
    environment:
      - NEW_ARRAY_ENTRY

Additional context
My current workaround is to use yq to transform the file into JSON, modifying with jq and using yq again to re-transform the result into YAML – which is actually very ugly:

yq --tojson eval '.' docker-compose.yml > docker-compose.json && \
  jq '.services[].environment += ["NEW_ARRAY_ENTRY"]' docker-compose.json | \
  yq eval -P > docker-compose.yml && \
  rm docker-compose.json;

[mikefarah]

Looks like a bug with '+=' :( I'll look into it asap - as a work around you can:

yq e '.services.*.environment |= . + ["cat"]' examples/data1.yaml

[mikefarah]

Fixed in 4.6.2

[ak-at-gvl]

Great! Thanks a lot for fixing this so quickly! 👍 🥳