'Docker-Compose file has yaml.scanner.ScannerError
compose.yml file, which looks like this:
version: '2'
services:
discovery-microservice:
build: discovery-microservice
context: /discovery-microservice/target/docker
dockerfile: Dockerfile
ports:
- "8761:8761"
While I am executing it I get the following error:
yaml.scanner.ScannerError: mapping values are not allowed here
in "C:\...\docker-compose.yml", line 5, column 14
From what I see, nothing is wrong with the format, e.g. whitespaces missing. My overall goal is to specify a development mode docker-compose file, pointing it to the target directories from the different modules.
What am I doing wrong here?
Solution 1:[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. :)
Solution 2:[2]
Ok, I wasted around 3 hours to debug a similar issue.
If you guys ever get the below error
ERROR: yaml.scanner.ScannerError: mapping values are not allowed here
in ".\docker-compose.yml", line 2, column 9
It's because a space is needed between
version:'3' <-- this is wrong
version: '3' <-- this is correct.
Also, if you are using eclipse, do yourself a favor and install the YEdit YAML editor plugin
Solution 3:[3]
And I forgot : after version
version '2'
Solution 4:[4]
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.
Solution 5:[5]
I met same issue and I think it's might be your yaml file format is invalid. So in order to solve it, first we need to make sure our yaml file format is valid
below is your original code snippet
version: '2'
services:
discovery-microservice:
build: discovery-microservice
context: /discovery-microservice/target/docker
dockerfile: Dockerfile
ports:
- "8761:8761"
If we use http://www.yamllint.com/ check the yaml file, we will get error as below:
Then we change it as below:
services:
discovery-microservice:
build: discovery-microservice
context: /discovery-microservice/target/docker
dockerfile: Dockerfile
ports:
- "8761:8761"
version: "2"
after checking it, we will get result as below:
Solution 6:[6]
Bringing my answer because while I got the same error message, my solution was different.
Original docker-compose.yml
volumes: mongo:
After trying all the ideas in this thread I just went to the docker-compose docks and realized that volumes should be structured like:
volumes:
mongo:
That's it for anyone else running into this.
Solution 7:[7]
Also make sure you have context and dockerfile at the same identation. I made a mistake and was stuck for hours.
My error was
ERROR: yaml.scanner.ScannerError: mapping values are not allowed here in "./docker-compose.yml", line 6, column 19
Wrong:
version : '3'
services:
test:
build:
context: ./test
dockerfile: Dockerfile.test
image: kpod/test:2020
Right:
version : '3'
services:
test:
build:
context: ./test
dockerfile: Dockerfile.test
image: kpod/test:2020
Solution 8:[8]
Hi further update to the given answer .... It's not specifically about the version: '2.0' line The statement
ERROR: yaml.scanner.ScannerError: mapping values are not allowed here
means there's a formatting error of some sort.
I got it and it was because I was missing a tab in my docker-compose file
version: '3.0'
services:
mysql:
image: ...
instead of
version: '3.0'
services:
mysql:
image: ...
Note the lack of an indenting tab on the image line
Solution 9:[9]
If you are using vs code do yourself a favor and install YAML extension by "RedHat".
Solution 10:[10]
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.
Solution 11:[11]
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
Solution 12:[12]
I found that missing one ":", was enough to produce the above error
Solution 13:[13]
I encountered a similar issue today, a syntax error in the docker-compose.yml file that caused the same error.
version: '2'
services:
// Add your services here
discovery-microservice:
build: discovery-microservice
context: ./discovery-microservice/target/docker
dockerfile: Dockerfile
ports:
- "8761:8761"
Removing this line // Add your services here fixed my issue
version: '2'
services:
discovery-microservice:
build:
context: ./discovery-microservice/target/docker
dockerfile: Dockerfile
ports:
- "8761:8761"
I hope this helps someone with a similar issue.
Solution 14:[14]
Another possible culprit can be stray tabs at the end of the file, which I learned today.
Solution 15:[15]
I wanted a volume mapped to a specific path on the external (host) server. I tried putting that under the top-level volumes entry in docker-compose.yml. After looking at the docker-compose file docs, I realized that that type of volume does not go there. Instead, it goes only under the volumes entry within the container definition. E.g.:
version: "3.7"
services:
web:
image: my_custom_web_image
build: ./app
volumes:
- ./app/subdir:/usr/src/app/subdir
Solution 16:[16]
Check your whitespaces by validating your YAML input.
I spent 1hour to find out.
Solution 17:[17]
So, there is another reason! When you try to install r=Redash using the setup.sh from the Github, the script automatically gets the latest version of Redash and put it in docker-compose.yml. The base yml file doesn't have single-quotations (') around version name! As a result, you get an error that says:
ERROR: yaml.scanner.ScannerError: mapping values are not allowed here in "./docker-compose.yml", line 3, column 23 You just add single-quotation around the Redash version:
version: "2"
x-redash-service: &redash-service
image: 'redash/redash:8.0.0.b32245'Solution 18:[18]
check for the space between
ports:
- _space_ "8080:8080"
Solution 19:[19]
For me the fix was adding the space between version: '2'
Also useful, when stipulating what the context field is, using ./ or the actual absolute path where the Dockerfile resides resolved this error:
ERROR: build path /Users/name/somepath/someapp either does not exist, is not accessible, or is not a valid URL.
Sources
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