We are using docker-compose to run some api tests. In the background, the API performs CRUD operations on a cosmsodb. The test run is supposed to run without creating and using a real cosmosdb, so i use the cosmosdb emulator as a docker image.
version: "3.7"
services:
cosmosdb:
image: mcr.microsoft.com/cosmosdb/linux/azure-cosmos-emulator
container_name: cosmosdb
environment:
- AZURE_COSMOS_EMULATOR_PARTITION_COUNT=10
- AZURE_COSMOS_EMULATOR_ENABLE_DATA_PERSISTENCE=true
healthcheck:
test:
[
"CMD",
"curl",
"-f",
"-k",
"https://localhost:8081/_explorer/emulator.pem",
]
interval: 10s
timeout: 1s
retries: 5
ports:
- "8081:8081"
init:
build:
context: init
depends_on:
cosmosdb:
condition: service_healthy
The script even has a loop to see if the db is ready, before writing anything. It works roughly like this:
const client = new CosmosClient({
endpoint: `https://cosmosdb:8081/`,
key: 'C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==',
connectionPolicy: { requestTimeout: 10000 },
});
async function isDbReady(): Promise<boolean> {
try {
await client.databases.readAll().fetchAll();
return true;
} catch (err) {
console.log('database not ready', err.message);
return false;
}
}
async function waitForDb(): Promise<void> {
while(!await isDbReady()) {
await new Promise((resolve) => setTimeout(resolve, 10000));
}
}
the problem, that we have is, when our script (javascript with @azure/cosmos) is trying to create a database, a couple of collections and then inserting a couple of items, the cosmosdb sometimes (about 20% of the tests) will just stop responding and run into timeouts. This will persist until we run docker-compose down and rerun docker-compose up for the next try.
We run a slightly modified version of the image, where we just installed curl for the healthcheck to run (the same issue happens when directly using mcr.microsoft.com/cosmosdb/linux/azure-cosmos-emulator which is why i simple added that image to the docker compose snippet). We use the healthcheck for cosmosdb emulator as suggested here: How to check if the Cosmos DB emulator in a Docker container is done booting?
Defining a docker-compose volume and mounting it as /tmp/cosmos/appdata also won't improve the situation.
We are also not sure how to set AZURE_COSMOS_EMULATOR_ENABLE_DATA_PERSISTENCE as we actually would like to start each test run with a clean database and have our script insert data.
How can we get the cosmosdb emulator to be more stable?
