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Configuration

Replace domain used in urls​

When uploading binaries to a configuration repository item, it can use the Cumulocity IoT url which includes the tenant name, for example a url like https://t12345.cumulocity.com/inventory/binaries/11111. Depending on your tenant setup, this URL might not be publicly reachable which might cause a problem to any agents/microservices want to download the binary behind the url.

Let's say that our Cumulocity IoT tenant is using a custom domain called https://mycompany.iot.com, however the configuration repository items are using urls the following the format; https://t12345.cumulocity.com/inventory/binaries/11111.

Replacing the domain can be done using the following chained command.

c8y configuration list --query "url eq '*https://t*/inventory/binaries/*'" \
| c8y inventory update \
    --template "{url: '$C8Y_HOST' + _.GetURLPath(input.value.url)}" \
    --dry

Explanation​

The solution involves two c8y commands:

  1. Find the configuration repository items which have a url which includes the tenant internal path (e.g. https://t12345.cumulocity.com/...)
  2. Update the .url field by replacing the existing host with the new one.

The first command finds the configuration repository items. It is important to use a query that only matches configuration items that are using the internal domain name. By doing this it ensures that the configuration item will not modified again if the command is run multiple times.

The second command uses a jsonnet template to do the domain name replacement. It uses the special _.GetURLPath() function provided by go-c8y-cli to make the manipulation of the URL much easier. The function returns the URL path without the domain/host. The function is applied to the configuration url by accessing the piped data (coming from the upstream configuration list command). The input.data contains the full representation of the current configuration item, so the url can be read by using using input.data.url. In addition the C8Y_HOST environment variable is referenced in the template (via shell expansion) so that you don't have to manually type the domain name making the command also portable to other tenants.

Before changing any data in the platform, it is best practice to validate the command first by following the points below:

  • Set the pageSize to 1 on the first command to limit the number of items.
  • Use the dry flag on the command which is modifying data. In this case it is the inventory update command.

We can check what the inventory update command will do (without sending any requests) for 1 configuration item using the following command:

c8y configuration list --query "url eq '*https://t*/inventory/binaries/*'" --pageSize 1 \
| c8y inventory update \
    --template "{url: '$C8Y_HOST' + _.GetURLPath(input.value.url)}" \
    --dry
Output
### PUT /inventory/managedObjects/541184560

| header            | value
|-------------------|---------------------------
| Accept            | application/json
| Authorization     | Bearer {token}
| Content-Type      | application/json

#### Body

```json
{
  "url": "https://mycompany.iot.com/inventory/binaries/1178209"
}
```

The output shows it would send a PUT request to the managed object api, and it will only update the .url fragment, and the .url fragment includes the correct domain name. So it looks like the command is doing everything it should, now the pageSize can be increased (or you can use the includeAll flag instead), and the dry flag can be removed.

c8y configuration list --query "url eq '*https://t*/inventory/binaries/*'" --includeAll \
| c8y inventory update \
    --template "{url: '$C8Y_HOST' + _.GetURLPath(input.value.url)}"