Docker-Compose file has yaml.scanner.ScannerError

Question

compose.yml file, which looks like this:

version: \'2\'
services:
  discovery-microservice:
    build: discovery-microservice
      context: /discov         


        

Answer 1

Literally found the solution seconds later. You have to remove the "discovery-microservice" after "build":

version: '2'
services:
  discovery-microservice:
    build:
      context: ./discovery-microservice/target/docker
      dockerfile: Dockerfile
    ports:
     - "8761:8761"

Also you can use "./" in context for relative paths. :)

Answer 2

What is wrong is that here:

    build: discovery-microservice

you start a mapping which has a key build indented by four spaces. The value for that key is a scalar that starts with discovery-microservice and possible continues to the next line, depending on whether that has a key: value pair at the same indentation level or not

What is not allowed inside such a multiline scalar is that you have an unquoted : and have that at a different indentation level. Which is exactly what you do have.

The parser seeing context indented at a different level than build assumes you are writing a scalar string discovery-microservice context which cannot be followed on the same line (as context) by a colon.

Apart from removing discovery-microservice after build as you did in your answer, what would also make this valid YAML (but with a different meaning, probably non-sense for docker compose) are:

services:
  discovery-microservice:
    build: "discovery-microservice
      context: /discovery-microservice/target/docker"

and

services:
  discovery-microservice:
    build: discovery-microservice
    context: /discovery-microservice/target/docker"

For docker-compose version 2 files, the build key expects a mapping (and not a scalar as in the "solutions" above), making your answer the correct way to solve this.

Answer 3

1) Give a space after every colon whenever you do mapping after defining key.

2) A YAML file uses 2(two spaces or tabs) indentation. -->It means that after every line you need to use two tabs,when you write a sentence in following line. I hope this will make easy to write any YAML file now.

Answer 4

check for the space between

ports:

- _space_ "8080:8080"

Answer 5

Using the vs code yaml RedHat extension, I saw I was off by one indent:

Wrong:

version: '3'

services:

  web:
    image: nginx
     ports:
    - 9090:80

  database:
    image: redis

Right:

version: '3'

services:

  web:
    image: nginx
    ports:
    - 9090:80

  database:
    image: redis

Answer 6

Another possible culprit can be stray tabs at the end of the file, which I learned today.