Govt. jobs are temporary or permanent?

Respected sir, My name is Mohammed Shadab and I am preparing for police and defence services but I have doubt in service nature or tenure job like IPS, IAS or any other government department specially police service this service or posts are permanent by constitution of India, any law for this in our constitution, any law that say government or public servant are permanent or temporary because of political interference is mostly involve in this services. On the time of appointment or confirmation of probationary officers any bond or letter for permanent post is given to the officers It is then assumed that only the Government and Public Service are permanent