CODEWITHSUNDEEP
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Spanky
Spanky

Reputation: 5778

How to get a list of internal IP addresses of GCE instances

I have a bunch of instances running in GCE. I want to programmatically get a list of the internal IP addresses of them without logging into the instances (locally).

I know I can run:

gcloud compute instances list

But are there any flags I can pass to just get the information I want? e.g.

gcloud compute instances list --internal-ips

or similar? Or am I going to have to dust off my sed/awk brain and parse the output?

I also know that I can get the output in JSON using --format=json, but I'm trying to do this in a bash script.

Upvotes: 13

Views: 19044

Answers (6)

pankaj singh
pankaj singh

Reputation: 21

The best possible way would be to have readymade gcloud command use the same as and when needed.

This can be achieved using table() format option with gcloud as per below:

gcloud compute instances list --format='table(id,name,status,zone,networkInterfaces[0].networkIP :label=Internal_IP,networkInterfaces[0].accessConfigs[0].natIP :label=External_IP)'

What does it do for you?

  • Get you data in clean format
  • Give you option to add or remove columns

Need additional columns? How to find column name even before you run the above command?

Execute the following, which will give you data in raw JSON format consisting value and its name, copy those names and add them into your table() list. :-)

gcloud compute instances list --format=json

Plus Point: This is pretty much same syntax you can tweak with any GCP resources data to fetch including with gcloud, kubectl etc.

Upvotes: 1

Dheerendra Nath
Dheerendra Nath

Reputation: 43

I hunted around and couldn't find a straight answer, probably because efficient tools weren't available when others replied to the original question. GCP constantly updates their libraries & APIs and we can use the filter and projections to extract targeted attributes.

Here I outline how to reserve an external static IP, see how it's attributes are named & organised, and then export the external IP address so that I can use it in other scripts (e.g. assign this to a VM instance or authorise this network (IP address) on a Cloud SQL instance.

Reserve a static IP in a region of your choice

gcloud compute --project=[PROJECT] addresses create [NAME] --region=[REGION]

[Informational] View the details of the regional static IP that was reserved

gcloud compute addresses describe [NAME] --region [REGION] --format=flattened

[Informational] List the attributes of the static IP in the form of key-value pairs

gcloud compute addresses describe [NAME] --region [REGION] --format='value(address)'

Extract the desired value (e.g. external IP address) as a parameter

export STATIC_IP=$(gcloud compute addresses describe [NAME] --region [REGION] --format='value(address)’)

Use the exported parameter in other scripts

echo $STATIC_IP

Upvotes: 4

Jeffrey Vaughan
Jeffrey Vaughan

Reputation: 894

A few things here.

First gcloud's default output format for listing is not guaranteed to be stable, and new columns may be added in the future. Don't script against this!

The three output modes are three output modes that are accessible with the format flag, --format=json, --format=yaml, and format=text, are based on key=value pairs and can scripted against even if new fields are introduced in the future.

Two good ways to do what you want are to use JSON and the jq tool,

gcloud compute instances list --format=json \
    | jq '.[].networkInterfaces[].networkIP'

or text format and grep + line-oriented using tools,

gcloud compute instances list --format=text \
    | grep '^networkInterfaces\[[0-9]\+\]\.networkIP:' | sed 's/^.* //g'

Upvotes: 10

aculich
aculich

Reputation: 14855

The simplest way to programmatically get a list of internal IPs (or external IPs) without a dependency on any tools other than gcloud is:

$ gcloud --format="value(networkInterfaces[0].networkIP)" compute instances list
$ gcloud --format="value(networkInterfaces[0].accessConfigs[0].natIP)" compute instances list

This uses --format=value which also requires a projection which is a list of resource keys that select resource data values. For any command you can use --format=flattened to get the list of resource key/value pairs:

$ gcloud --format=flattened compute instances list

Upvotes: 35

Adrián
Adrián

Reputation: 2880

I agree with @Christiaan. Currently there is no automated way to get the internal IPs using the gcloud command.

You can use the following command to print the internal IPs (4th column):

gcloud compute instances list | tail -n+2 | awk '{print $4}'

or the following one if you want to have the pair <instance_name> <internal_ip> (1st and 4th column)

gcloud compute instances list | tail -n+2 | awk '{print $1, $4}'

I hope it helps.

Upvotes: 0

Christiaan
Christiaan

Reputation: 2725

As far as I know you can't filter on specific fields in the gcloud tool. Something like this will work for a Bash script, but it still feels a bit brittle:

gcloud compute instances list --format=yaml | grep "  networkIP:" | cut -c 14-100

Upvotes: 0

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