Category Archives: How-to

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OBI formatting grand totals – without XML!

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Recently I needed to have some conditionally formated grand total rows in OBI. I remember years ago hacking around with the XML which is far from ideal. I then realised it could be done another way, here is the example:

 

Create an analysis with a measure column:

Apply the conditional format on the Actual % column

This should result in the following analysis

This is the special bit, add a new calculated item on the column where you want the total

Select the Function (aggregation Rule) and add in all of the values

Now the totals will be applied to the analysis

You can format this calculated row using the format option on the calculated item window


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Start/ Stop Container Using The Proxmox Web API in Bash

Category : How-to

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The Proxmox Web API can perform any actions available in the front end Web. By implementing a REST API, all commands have been exposed and can be used programatically.

In this example we’ll use Bash to call the Proxmox Web API with our authentication token to start and stop an existing LXC Container.

See this post for an introduction to the Proxmox Web API, including all available API commands.

To issue API requests you’ll need to ensure you have already generated an authentication ticket which is described in Parse Proxmox Web API authentication ticket and the CSRFPreventionToken in Bash.

Once you have the authentication ticket you’ll need to call the Proxmox API using curl and parse the result. Use the below scripts and substitute the values as required:

Start an LXC Container

  • TICKET is the authentication ticket that was produced in the Parse Proxmox Web API authentication ticket and the CSRFPreventionToken in Bash post. Ideally you would programatically call the authentication routine and then pass the values straight into the below API calls.
  • CSRF is produced in the same way as TICKET. It’s actually only required when writing data to the API but there is no harm in always including it.
  • HOST is the host or IP address of the Proxmox server.
  • NODE is the node name of the Proxmox server that the LXC Container resides on.
  • TARGET_VM  is the VMID of the LXC Container.

If $START_TASK_RESULT doesn’t come back with null or empty then the command has successfully executed.

Stop an LXC Container

Stopping a VM in Proxmox is very similar to starting one, with just a slight change to the API URL call. All other options are the same as the above section ‘Start an LXC Container’.

If $STOP_TASK_RESULT doesn’t come back with null or empty then the command has successfully executed.


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Getting Started With Proxmox HTTP API Commands

Category : How-to

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Proxmox has 2 API access points that can be used to control your Proxmox server and virtual guests. One of the API access points is using the command line, which you’re likely already familiar with. The other is the HTTP web API which is exposed as part of the WEB GUI on port 8006.

The Proxmox uses a JSON data format for returning data that can easily be parsed programmatically. Every command available to the pvesh command line command are available to the web based API as they share the same endpoint.

The endpoint for the Web API can be called using anything that can send and receive web based requests. We’ll use curl for the below examples. The endpoint to call would be similar to below – be sure you substitute yourip for the IP or hostname of your Proxmox server.

API Authentication

The next step is to authenticate your API requests with the Proxmox server. API authentication uses the same mechanism that logging into the Web GUI uses and requires a username, password and security realm.

Authentication is based on a token method which provides a ticket that must accompany all API requests except for the request that generates the token. A username and password will not be accepted for authentication with all other API requests. In addition, any requests that POST or write to the API endpoint must contain a CSRF Prevention Token.

To obtain an authentication token, run the below curl command and substitute your values as required – this example uses the root user and the default PAM realm.

Example output:

The two interesting parts here are the ticket value and the CSRFPreventionToken and should be parsed out for use in later requests.

A token is valid for 2 hours and should be re-requested when it expires. Alternatively each request could generate it’s own token, however this generates added overhead.

List of Proxmox API Requests

pvesh is a command line utility can be used to perform the same actions as the web based API. You can, therefore, use the pvesh command to list all the possible API calls and navigate through the API call tree.

You can then list the available commands from the root of the API using ls and then change into one of the child paths using cd. You can navigate throughout the whole API tree using these two methods to see what commands are available for calling. This is often the best way to get started with the Proxmox API.

Examples of API Requests

As stated earlier, all operations available in the Proxmox Web GUI can be performed through the API. Here are a few examples of API requests using Bash:


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Parse Proxmox Web API authentication ticket and the CSRFPreventionToken in Bash

Category : How-to

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The Proxmox Web API can perform any actions available in the front end Web. By implementing a REST API, all commands have been exposed and can be used programatically.

The API is secured using a token based method which provides a ticket that must accompany all API requests except for the request that generates the token. The token is generated from an API call containing a username, password and security realm.

In this example we’ll use Bash to call the Proxmox Web API, authenticate with the root Proxmox user and parse the response for use in later API requests. Note that it’s not good practice to use the root account for API calls due to the security implications.

See this post for an introduction to the Proxmox Web API.

Add this function to the top of your Bash script. This will be used to parse the JSON using standard Bash calls to obtain the information we need.

The next step is to call the Proxmox API using curl to obtain our authentication token. Use the below script and substitute the values as required:

  • PROX_USERNAME is the username and security realm used to log into the Proxmox Web front end. This must be a valid user with the required permission to make the calls you need.
  • PROX_PASSWORD is the password for the above user. You must escape any special characters as usual in Bash.
  • HOST is the host or IP address of the Proxmox server.

And that’s all there is to it! You can use the variables $TICKET and $CSRF in later requests. Keep in mind that a valid ticket is only valid for 2 hours, after that you’ll need to create a new one.


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Virgin Media Speeds In Nottingham

Category : How-to

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Somewhat off-topic today, but something that I’ve recorded here to showcase the current state and see if anyone else is getting similar issues.

A colleague of mine and I have been measuring our broadband speeds since the start of the year. We both live in Nottingham and pay for a residential Virgin Media 200mbps line which I pay approximately £45 each month.

Given the data logged, we’ve concluded that our upload is typically fine at 12mbps but the download varies massively – to the point where single session streaming from Youtube/Netflix is unusable.

This graph shows average download speed per hour which clearly shows the drop during the ‘busy period’

This next one shows the number of counts recorded at a given speed range for the best time (5am) and worse time (9pm). As you can see at 9pm I mostly get between 30mbps and 80mbps

Another way to look at this is via a heatmap showing counts for all speed groups by hour:

We then wondered what the cost implication of this could be, if we only paid for what we got. The table below shows calculations of the cost impact. It is based on cost per month divided by 24 (number of hours) then working out the modified hourly rate based on that percentage.

Being fair, I would ignore speeds where the fluctuation is less than 20% and pay the full price for that hour. An 80% drop in speed is perfectly reasonable in my book and something that probably wouldn’t be noticed by most people. Using the above calculation the result would be a cost of £33.42, meaning I’m overcharged by ~35%.

These are average speeds, and as shown above the download speed can be much lower than this average and it’s at these points the impact to me is most interruptive to me and this cost isn’t reflected above.

How are other peoples download speeds stacking up?


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Simple iptables Rules for Ubuntu/ Debian VPS

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The following iptables rules are are a starting point to add basic firewall security to a public facing server, such as a public VPS. The primary focus is to stop any inbound traffic other than SSH, which is required for shell access.

The biggest issue with public VPS providers is that often some iptables features are disabled – many OpenVZ container providers don’t allow state checking in iptables, for example. If you’ve got one of these VPS’s you’ll likely see the following error:

These rules are engineered so that they will work with most VPS’s where iptables is installed.

The following rules will block all incoming connections except SSH, including PING requests. Outgoing is open for HTTP and HTTPS TCP requests and DNS UDP requests.

See the links at the bottom of the page for a more in depth look at iptables rules.

If you’re using Ubuntu, you can easily make the rules persist: